Monitoring device, monitoring method and method of manufacturing semiconductor device using reflectivity of wafer

ABSTRACT

Provided are a monitoring device and method. A monitoring device includes a laser processor configured to emit a processing laser beam to perform a melting annealing process on a wafer; a laser monitor configured to emit a monitoring laser beam onto the wafer while the laser processor performs the melting annealing process, the laser monitor configured to measure reflectivity of the wafer; and a data processor configured to process data on the reflectivity measured by the laser monitor, and monitor one or more characteristics of the wafer based on the data on the reflectivity.

This application claims priority under 35 USC § 119 to Korean PatentApplication No. 10-2018-0105078, filed on Sep. 4, 2018, in the KoreanIntellectual Property Office, the disclosure of which is incorporatedhereby in its entirety by reference.

BACKGROUND 1. Field

The present disclosure relates to a monitoring device and method. Thepresent disclosure also relates to a method of manufacturing asemiconductor device.

2. Description of the Related Art

Among various processes performed in the manufacture of a semiconductordevice, a melting annealing process is a process of melting the surfaceof a wafer by heating the wafer to a high temperature. Although thereare various methods of heating a wafer, a method of heating an upperportion of a wafer to a high temperature by using a laser is often used.In particular, a recent melting annealing process is performed forseveral nanoseconds to several tens of nanoseconds. Thus, semiconductordevices are heated and melted for a very short time.

When a wafer is melted according to such a melting annealing process, itis beneficial to perform in-situ monitoring in order to manage processdispersion, productivity, quality, etc. and to check whether the waferis melted to an intended level. For example, in-situ monitoring may beused to identify the characteristics of the wafer on which the meltingannealing process is performed, such as whether a melting depthcorresponds to an intended depth and whether the wafer is evenly melted.

However, when a melting process is performed for a very short time ofseveral nanoseconds to several tens of nanoseconds as mentioned above, amethod of precisely monitoring the melting process during that time ishelpful.

SUMMARY

Aspects of the present disclosure provide a monitoring device and methodcapable of precisely in-situ monitoring a melting annealing processperformed for a very short time of several nanoseconds to several tensof nanoseconds.

Aspects of the present disclosure also provide a monitoring device andmethod capable of in-situ identifying the characteristics of a wafer onwhich a melting annealing process is performed.

However, aspects of the present disclosure are not restricted to the oneset forth herein. The above and other aspects of the present disclosurewill become more apparent to one of ordinary skill in the art to whichthe present disclosure pertains by referencing the detailed descriptionof the present disclosure given below.

According to an aspect of the present disclosure, there is provided amonitoring device including a laser processor configured to emit aprocessing laser beam to perform a melting annealing process on a wafer;a laser monitor configured to emit a monitoring laser beam onto thewafer while the laser processor performs the melting annealing process,the laser monitor configured to measure reflectivity of the wafer; and adata processor configured to process data on the reflectivity measuredby the laser monitor, and monitor one or more characteristics of thewafer based on the data on the reflectivity.

According to another aspect of the present disclosure, there is provideda monitoring device including a support configured to receive a wafercomprising a first die and a second die; a laser processor configured toperform a first melting annealing process by emitting a processing laserbeam to the first die and a second melting annealing process by emittingthe processing laser beam to the second die; first and second lightsensors; a laser monitor configured to measure first reflectivity of thefirst die in combination with the first and second light sensors byemitting a monitoring laser beam to the first die while the laserprocessor performs the first melting annealing process, the lasermonitor configured to measure second reflectivity of the second die incombination with the first and second light sensors by emitting themonitoring laser beam to the second die while the laser processorperforms the second melting annealing process; and a data processorconfigured to monitor characteristics of the wafer based on the firstreflectivity and the second reflectivity measured by the laser monitor.

According to still another aspect of the present disclosure, there isprovided a monitoring device including a laser processor configured toperform a melting annealing process on a wafer by emitting a processinglaser beam to the wafer; first and second light sensors configured toreceive light signal; a laser monitor configured to measure reflectivityof the wafer in combination with the first and second light sensors byemitting a monitoring laser beam to the wafer while the laser processorperforms the melting annealing process; a thermal detector configured todetect temperature of a surface of the wafer while the laser processorperforms the melting annealing process; a controller configured tocontrol at least one of the laser processor, the laser monitor and thethermal detector; and a feedback circuit configured to provide thecontroller with feedback data according to a value of at least one ofthe measured reflectivity and temperature, wherein the controller isconfigured to adjust a setting of at least one of the laser processor,the laser monitor and the thermal detector according to the feedbackdata.

According to still another aspect of the present disclosure, there isprovided a monitoring method including performing a melting annealingprocess on a wafer by emitting a processing laser beam to the wafer;measuring reflectivity of the wafer by emitting a monitoring laser beamto the wafer while the melting annealing process is performed; andmonitoring characteristics of the wafer based on the measuredreflectivity.

BRIEF DESCRIPTION OF THE DRAWINGS

These and/or other aspects will become apparent and more readilyappreciated from the following description of the embodiments, taken inconjunction with the accompanying drawings in which:

FIG. 1 is a schematic diagram of a monitoring system according to anembodiment;

FIG. 2 illustrates a monitoring device according to an embodiment;

FIG. 3 illustrates a wafer on which a melting annealing process andmonitoring are performed according to an embodiment;

FIGS. 4 through 6 are diagrams for explaining the operation of measuringthe reflectivity of a wafer using the monitoring device of FIG. 2;

FIG. 7 is a graph illustrating an example of change in reflectivitymeasured by the monitoring device according to the embodiment;

FIG. 8 is a graph illustrating the relationship between melting durationand melting depth;

FIG. 9 is a graph illustrating another example of change in reflectivitymeasured by the monitoring device according to the embodiment;

FIG. 10 is a diagram for explaining that reflectivity may vary accordingto the type of film;

FIG. 11 is a graph illustrating another example of change inreflectivity measured by the monitoring device according to theembodiment;

FIG. 12 is a diagram for explaining that reflectivity may vary accordingto the melting depth;

FIG. 13 is a diagram for explaining the operation of measuring thetemperature of the surface of the wafer using the monitoring device ofFIG. 2;

FIG. 14 is a graph illustrating the relationship between the temperatureof the wafer surface and the melting depth;

FIG. 15 is a graph illustrating the relationship between the temperatureof the wafer surface and sheet resistance;

FIGS. 16 and 17 are diagrams for explaining a monitoring deviceaccording to an embodiment;

FIGS. 18 and 19 are diagrams for explaining the operation of measuringthe reflectivity of a wafer using the monitoring device of FIG. 16;

FIG. 20 is a diagram for explaining the operation of measuring thetemperature of the surface of the wafer using the monitoring device ofFIG. 16;

FIG. 21 is a schematic diagram of a monitoring system according to anembodiment;

FIG. 22 is a flowchart illustrating a monitoring method according to anembodiment;

FIG. 23 is a flowchart illustrating a monitoring method according to anembodiment; and

FIG. 24 is a flowchart illustrating a monitoring method according to anembodiment.

DETAILED DESCRIPTION

FIG. 1 is a schematic diagram of a monitoring system 1 according to anembodiment.

Referring to FIG. 1, the monitoring system 1 according to the embodimentmay include a processing laser unit 10, a monitoring laser unit 20, athermal detecting unit 30, and a control board 40.

The processing laser unit 10 may perform a melting annealing process ona wafer W by emitting a processing laser beam 12 to the wafer W. Forexample, the processing laser unit 10 emits the processing laser beam 12in order to heat an upper portion of the wafer W to a high temperature,and the high temperature at this time may be, for example, about 1,200°C. or more. For example, the processing laser unit 10 may melt the upperportion of the wafer W using the processing laser beam 12 for a shorttime of several nanoseconds to several tens of nanoseconds. Theprocessing laser unit 10 and other components having the same name inthe other embodiments of the current disclosure may be a laserprocessor. The processing laser beam 12 and other components having thesame name in the other embodiments of the current disclosure are laserbeams.

In an embodiment, the wafer W may be heated first by a heater chuck HTbefore being heated to a high temperature by the processing laser beam12. For example, the heater chuck HT serves not only to support thewafer W but also to heat the wafer W before the emission of theprocessing laser beam 12. The heater chuck HT may heat the wafer W to atemperature from about 200° C. to about 400° C. For example, the heaterchuck HT may include an electric heating element, e.g., nichrome,cupronickel, etc., in the heater chuck HT.

In the current embodiment, the processing laser beam 12 may have awavelength of, for example, 532 nm. In certain embodiments, theprocessing laser beam may include a light wave having wavelength between450 nm and 600 nm.

The monitoring laser unit 20 may perform in-situ monitoring of thecharacteristics of the wafer W, on which the melting annealing processis performed, based on the reflectivity of the wafer W that may beidentified through a monitoring laser beam 22 and reflected light 23.For example, the reflected light 23 may be a portion of the monitoringlaser beam 22 indecent on a surface of the wafer W. For example, whilethe processing laser unit 10 performs the melting annealing process, themonitoring laser unit 20 may perform in-situ monitoring by emitting themonitoring laser beam 22 to the wafer W, receiving the reflected light23 and measuring the reflectivity of the wafer W based on the receivedreflected light 23. The monitoring laser unit 20 and other componentshaving the same name in the other embodiments of the current disclosuremay be referred to as a laser monitor in that the monitoring laser unitsmonitor characteristics of wafers with laser beams. The monitoring laserbeam 22 and other components having the same name in the otherembodiments of the current disclosure are laser beams and may be calledas a monitoring laser beam.

For example, the monitoring laser unit 20 may measure the reflectivityof the wafer W by comparing the intensity of the monitoring laser beam22 incident on the wafer W with the intensity of the reflected light 23reflected from the wafer W. However, a specific method of measuringreflectivity may vary depending on the implementation method.

In the current embodiment, the monitoring laser beam 22 may have awavelength of, for example, 658 nm. In certain embodiments, themonitoring laser beam 22 may include a light wave having a wavelengthbetween 600 nm and 700 nm.

The thermal detecting unit 30 may perform in-situ monitoring of thecharacteristics of the wafer W, on which the melting annealing processis performed, based on the temperature of the surface of the wafer Wthat may be identified through emitted heat 32. For example, the thermaldetecting unit 30 may perform in-situ monitoring by detecting thetemperature of the surface of the wafer W while the processing laserunit 10 performs the melting annealing process. The thermal detectingunit 30 may be a thermal detector.

In the current embodiment, the thermal detecting unit 30 may include anInGaAs sensor.

In the current embodiment, the thermal detecting unit 30 may detect thetemperature of the surface of the wafer W by receiving a signal of awavelength of 1550 nm of the emitted heat 32. In certain embodiments,the thermal detecting unit 30 may determine the temperature of thesurface of the wafer by receiving an electromagnetic wave having awavelength between 1000 nm and 2000 nm.

The control board 40 may control the monitoring system 1 according tothe embodiment and may include a control unit 42 and a data processingunit 44.

The control unit 42 may control at least one of the processing laserunit 10, the monitoring laser unit 20 and the thermal detecting unit 30.For example, the control unit 42 may perform control such as changingthe wavelength of the processing laser beam 12 emitted from theprocessing laser unit 10, adjusting the power, or adjusting the emissiontime. For another example, the control unit 42 may perform control suchas changing the wavelength of the monitoring laser beam 22 emitted fromthe monitoring laser unit 20 or adjusting the emission time. The controlunit 42 may be a controller, and may include a logic circuit integratedin a semiconductor chip.

The data processing unit 44 may process data on the reflectivitymeasured by the monitoring laser unit 20 or processes data on thetemperature measured by the thermal detecting unit 30. Thecharacteristics of the wafer W may be monitored based on these data. Thedata processing unit 44 may be a data processor including a logiccircuit, e.g., a processor chip and/or other semiconductor chips.

Here, the characteristics of the wafer W refer to the characteristics ofthe wafer W on which the melting annealing process is performed. Forexample, the characteristics of the wafer W may include the meltingdepth of the wafer W, the uniformity of the melting depth, the size ofgrains, the doping concentration of a film, the type of the film, andthe sheet resistance of the film.

For example, the melting depth of the wafer W is a characteristicindicating the depth of the upper portion of the wafer W where meltingis caused by the processing laser beam 12. The uniformity of the meltingdepth is a characteristic indicating whether the depth at which themelting occurs is uniform across the entire area or across apredetermined area of the wafer W. The size of the grains is acharacteristic indicating the size of grains formed by particles in amelted portion after the melting of the upper portion of the wafer W isperformed/completed. The doping concentration of the film is acharacteristic indicating the doping concentration of a semiconductorfilm formed on the wafer W. The type of the film is a characteristicindicating whether the semiconductor film formed on the wafer W is madeof, for example, amorphous silicon, polysilicon, or crystalline silicon.

Regarding FIG. 2, a monitoring device according to an embodiment willnow be described in terms of implementing the processing laser unit 10,the monitoring laser unit 20 and the thermal detecting unit 30.

FIG. 2 illustrates a monitoring device 2 according to an embodiment.

Referring to FIG. 2, the monitoring device 2 according to the embodimentincludes a processing laser unit 10, a monitoring laser unit 20 and athermal detecting unit 30 as described above with reference to FIG. 1.

The processing laser unit 10 may include a processing laser emitter 100,lenses 110 and 112, and a path changing optics 111.

The processing laser emitter 100 emits a processing laser beam 12 formelting an upper portion of a wafer W. The path of the processing laserbeam 12 reaching the path changing optics 111 via the lens 110 ismodified such that the processing laser beam 12 travels toward the waferW. The processing laser beam 12 whose path has been modified passesthrough the lens 112 and then reaches the wafer W. For example, theprocessing laser beam 12 may be a laser beam, and the processing laseremitter 100 may emit the processing laser beam and may also be referredto as a processing laser beam emitter. This description may be similarlyapplied to the other embodiments of the present disclosure.

The monitoring laser unit 20 includes a monitoring laser emitter 200, afirst light receiving unit 210, a second light receiving unit 212,lenses 220, 223 and 225, path changing optics 221 and 227, and filters224 and 226.

The monitoring laser emitter 200 emits a monitoring laser beam 22 forin-situ monitoring of the characteristics of the wafer W on which amelting annealing process is performed, and the reflectivity of thewafer W is measured using the first light receiving unit 210, the secondlight receiving unit 212, the lenses 220, 223 and 225, the path changingoptics 221 and 227, and the filters 224 and 226. This will be describedin more detail later with reference to FIGS. 4 through 6. The first andsecond light receiving units 210 and 212 may receive light signals andmay be respectively referred to as a first light receiver and a secondlight receiver and may respectively include a first light sensor and asecond light sensor (e.g., photodetectors), and light receiving unitsthroughout the present disclosure may be also respectively called aslight receivers or light sensors. For example, the first and secondlight receiving units 210 and 212 may be photodetectors, such asphotodiodes.

The thermal detecting unit 30 may include a thermal sensor 300, a lens310, and a filter 311.

The thermal sensor 300 senses heat 32 emitted from the wafer W on whichthe melting annealing process is performed by using the lens 310 and thefilter 311. This will be described in more detail later with referenceto FIG. 13.

It should be noted that the configuration of the monitoring device 2illustrated in FIG. 2 is merely an embodiment, and the detailedconfiguration of the processing laser unit 10, the monitoring laser unit20 and the thermal detecting unit 30 may be modified variously accordingto the purpose of implementation.

FIG. 3 illustrates a wafer W on which a melting annealing process andmonitoring are performed according to an embodiment.

Referring to FIG. 3, a plurality of dies D are formed on the wafer Wsupported by the heater chuck HT. Semiconductor devices are formed oneach of the dies D, and each die D on which the semiconductor deviceshave been formed may be sliced into a plurality of chips. Each of thechips may then be packaged and completed as a product.

In an embodiment, the processing laser unit 10 may perform a meltingannealing process on the wafer W on a die-by-die basis. For example, theprocessing laser unit 10 may perform a first melting annealing processby emitting the processing laser beam 12 to a first die D1 and thenperform a second melting annealing process by emitting the processinglaser beam 12 to a second die D2.

For example, the processing laser unit 10 may melt an upper portion ofthe first die D1 by emitting the processing laser beam 12 to the firstdie D1 and then melt an upper portion of the second die D2 by emittingthe processing laser beam 12 to the second die D2. After processing thesecond die D2, the processing laser unit 10 may melt an upper portion ofa third die D3 by emitting the processing laser beam 12 to the third dieD3.

The above description of the first through third dies D1 through D3 ismerely an example, and the scope of the present disclosure is notlimited to the above order. For example, the processing laser unit 10may perform a melting annealing process on the wafer W on a die-by-diebasis in any predetermined order.

One of the reasons for performing the melting annealing process on adie-by-die basis is that the power of the processing laser beam 12 maybe insufficient to heat the entire area of the wafer W to a hightemperature. In certain embodiments, the power of the processing laserbeam 12 may be enough to heat plural dies together at a time, andseveral dies may be heated to a high temperature. For example, theprocessing laser unit 10 may perform a melting annealing process inunits of several dies D (e.g., in units of two dies D or in units ofthree or more dies D).

In the above embodiment illustrated in FIG. 3, the monitoring laser unit20 may measure the reflectivity of the wafer W for each die D formed onthe wafer W. For example, the monitoring laser unit 20 may measure firstreflectivity of the first die D1 by emitting the monitoring laser beam22 to the first die D1 while the processing laser unit 10 performs thefirst melting annealing process and then measure second reflectivity ofthe second die D2 by emitting the monitoring laser beam 22 to the secondfirst die D2 while the processing laser unit 10 performs the secondmelting annealing process.

The data processing unit 44 may then monitor the characteristics of thewafer W based on data about the first reflectivity and the secondreflectivity measured by the monitoring laser unit 20.

Likewise, in the current embodiment, the thermal detecting unit 30 maydetect the temperature of the surface of the wafer W for each die Dformed on the wafer W. For example, the thermal detecting unit 30 maydetect a first temperature of the surface of the first die D1 while theprocessing laser unit 10 performs the first melting annealing processand then detect a second temperature of the surface of the second die D2while the processing laser unit 10 performs the second melting annealingprocess.

The data processing unit 44 may then monitor the characteristics of thewafer W based on data about the first temperature and the secondtemperature measured by the thermal detecting unit 30.

In certain embodiments, the power of the processing laser beam 12 mayallow that several dies together may be heated at a time to a hightemperature, and the processing laser unit 10 may perform a meltingannealing process in units of several dies D (e.g., in units of two diesD or in units of three or more dies D), and the monitoring laser unit 20and the thermal detecting unit 30 may also measure reflectivity anddetect temperature in units of several or more dies D at a time.

FIGS. 4 through 6 are diagrams for explaining the operation of measuringthe reflectivity of a wafer W using the monitoring device 2 of FIG. 2.

Referring to FIG. 4, the monitoring laser unit 20 may include themonitoring laser emitter 200, the first light receiving unit 210, thesecond light receiving unit 212, the lenses 220, 223 and 225, the pathchanging optics 221 and 227, and the filters 224 and 226.

The monitoring laser emitter 200 of the monitoring laser unit 20 emitsthe monitoring laser beam 22 while the processing laser unit 10 performsa melting annealing process using the processing laser beam 12. Themonitoring laser beam 22 passes through the lens 220 and changes itstravelling direction to the wafer W according to the path changingoptics 221. The monitoring laser beam 22 that has changed its travelingdirection travels to the first light receiving unit 210 and the pathchanging optics 111 according to the path changing optics 227.

The first light receiving unit 210 receives the monitoring laser beam 22incident on the wafer W. However, when the first light receiving unit210 directly receives the monitoring laser beam 22 itself, themonitoring laser beam 22 may not reach the wafer W. Therefore, the firstlight receiving unit 210 receives reference light 22 b traveling along apath branched by the path changing optics 227. For example, the pathchanging optics 227 may split the monitoring laser beam 22 into twolaser beams and send one of them to the wafer W and the other of them tothe light receiving unit 210.

For example, the reference light 22 b travelling along the path branchedfrom the monitoring laser beam 22 by the path changing optics 227 passesthrough the lens 223 and the filter 224 and enters the first lightreceiving unit 210. In an embodiment, the filter 224 may be a filter forpassing light having a wavelength of, e.g., 658 nm. In certainembodiments, the path changing optics 227 may reflect/transmit themonitoring laser beam 22 toward the light receiving unit 210 in a firstperiod of time, and toward the wafer W in a second period of time.

A monitoring laser beam 22 a travelling to the path changing optics 111may pass through the lens 112 and enter the wafer W. Here, referring toFIG. 5, when the monitoring laser beam 22 a is incident on a die D, across section of the incident light 22 a may be represented by an area Aas illustrated in FIG. 5.

Next, referring to FIG. 6, the second light receiving unit 212 receivesthe reflected light 23 reflected from the wafer W. The reflected light23 passes through the lens 112 and the path changing optics 111 and thenchanges its travelling direction to the second light receiving unit 212according to the path changing optics 227. For example, the pathchanging optics 227 may change the path of at least a portion or all ofthe reflected light coming from the wafer W so that the portion or allof the reflected light incident to the second light receiving unit 212.The reflected light 23 that has changed its traveling direction passesthrough the lens 225 and the filter 226 and enters the second lightreceiving unit 212. In an embodiment, the filter 226 may be a filter forpassing light having a wavelength of, e.g., 658 nm.

The monitoring laser unit 20 may measure reflectivity using the firstlight receiving unit 210 and the second light receiving unit 212. Forexample, the monitoring laser unit 20 may measure reflectivity bycomparing the intensity of the reference light 22 b received through thefirst light receiving unit 210 with the intensity of the reflected light23 received through the second light receiving unit 212.

For example, when the processing laser unit 10 performs a meltingannealing process on the wafer W on a die-by-die basis as described withrespect to FIG. 3, the monitoring laser unit 20 may measure the firstreflectivity of the first die D1 and the second reflectivity of thesecond die D2 by comparing the intensities of the monitoring laser beam22 incident on the first die D1 and the second die D2 with theintensities of the reflected light 23 reflected from the first die D1and the second die D2, respectively.

Here, the first light receiving unit 210 may receive the monitoringlaser beam 22 incident on the first die D1 and the second die D2, thesecond light receiving unit 212 may receive the reflected light 23reflected from the first die D1 and the second die D2, and themonitoring laser unit 20 may measure reflectivity by using the firstlight receiving unit 210 and the second light receiving unit 212.

FIG. 7 is a graph illustrating an example of change in reflectivitymeasured by the monitoring device 2 according to the embodiment.

Referring to FIG. 7, the change in reflectivity measured by themonitoring device 2 as described above may be divided into a firstsection M1, a second section M2, and a third section M3.

The first section M1 refers to a section before the melting of an upperportion of a wafer W is started. For example, in the first section M1 ofthe reflectivity, the portion of the wafer W, e.g., the surface of thewafer W, on which the monitoring laser beam is incident and from whichthe monitoring laser beam is reflected may be in solid state. In thefirst section M, the reflectivity measured by the monitoring laser unit20 may have a value of, e.g. R1.

The second section M2 is a section in which the melting of the upperportion of the wafer W occurs. In the second section M2, a firstsub-section from a time T2 to a time T3 is a period in which the upperportion of the wafer W melts from a solid to a liquid, and thereflectivity measured by the monitoring laser unit 20 may increase fromR1 to, e.g., R3 in this section.

In the second section M2, a second sub-section from the time T3 to atime T4 is a period in which the upper portion of the wafer W may beonly in the liquid state. For example, the measured area of the wafer Wmay be all liquid state in the second sub-section. The secondsub-section may be defined as melting duration MD. The reflectivitymeasured by the monitoring laser unit 20 in this section may bemaintained at, e.g., R3.

In the second section M2, a section from the time T4 to a time T5 is asection in which the emission of the processing laser beam 12 is stoppedand the upper portion of the wafer W starts to be cooled. Thereflectivity measured by the monitoring laser unit 20 may start to fallfrom R3 in this section.

The third section M3 is a section in which the upper portion of thewafer W is cooled down. When the upper portion of the wafer W is cooledin the third section M3, the size of grains that form the upper portionof the wafer W increases. For example, the grain size at a time T6 ofthe third section M3 is larger than the grain size at the time T1 of thefirst section M1, and the reflectivity R2 measured at the time T6 of thethird section M3 by the monitoring laser unit 20 has a larger/greatervalue than the reflectivity R1 measured at the time T1 of the firstsection M1 by the monitoring laser unit 20.

It should be noted that the pattern of change in reflectivityillustrated in FIG. 7 may vary depending on the specific environment orcondition of a melting annealing process. However, the monitoring device2 of the present disclosure may define the pattern of change inreflectivity in a specific environment and condition as a referencepattern and then monitor the characteristics of the wafer W by comparingreflectivity obtained during an actual melting annealing processperformed under the same or similar environment and condition with thereference pattern.

FIG. 8 is a graph illustrating the relationship between the meltingduration and the melting depth.

Referring to FIG. 8, the melting duration MD described with respect toFIG. 7 and the melting depth of the upper portion of the wafer W mayhave a substantially proportional relationship. Therefore, when themelting duration MD1 is relatively short as a result of analyzing thechange in reflectivity, it may be predicted that the melting depth DEP1of the upper portion of the wafer W is relatively shallow. Conversely,when the melting duration MD2 is relatively long, it may be predictedthat the melting depth DEP2 of the upper portion of the wafer W isrelatively deep. The term “substantially” may be used in the presentdisclosure to emphasize this meaning, unless the context or otherstatements indicate otherwise. For example, items described as“substantially proportional,” “substantially the same,” “substantiallyequal,” or “substantially planar,” may be exactly proportional, thesame, equal, or planar, or may be the same, equal, or planar withinacceptable variations that may occur, for example, due to manufacturingprocesses.

Accordingly, the data processing unit 44 of the control board 40according to the embodiment may judge the melting duration based on dataabout the reflectivity measured by the monitoring laser unit 20 andpredict the melting depth based on the length of the melting duration.

FIG. 9 is a graph illustrating another example of change in reflectivitymeasured by the monitoring device 2 according to the embodiment.

Referring to FIG. 9, the doping concentration of a film coated on thewafer W may be identified by analyzing the change in reflectivity.

For example, when the film coated on the wafer W in a process prior to amelting annealing process has a doping concentration of, e.g., 7E20, thechange in reflectivity may be represented by a graph C1. Alternatively,when the film coated on the wafer W in the process prior to the meltingannealing process has a doping concentration of, e.g., 11E20, the changein reflectivity may be represented by a graph C2.

In this case, when there is a constraint/precondition that the filmcoated on the wafer W must satisfy the doping concentration of, e.g.,7E20 in order for the melting annealing process to be performed, whenreflectivity data shows the trend of the graph C2 as a result ofanalyzing the change in reflectivity measured by the monitoring laserunit 20, it may be determined that a problem or failure may haveoccurred in a previous process.

For example, the data processing unit 44 of the control board 40according to the embodiment may predict the failure of the previousprocess based on data about the reflectivity measured by the monitoringlaser unit 20.

FIG. 10 is a diagram for explaining that reflectivity may vary accordingto the type of film.

Referring to FIG. 10, the type of the film coated on the wafer W may beidentified by analyzing reflectivity.

For example, the change in reflectivity may be represented by differentgraphs when the film coated on the wafer W in a process beforeperforming the melting annealing process is made of amorphous silicon(a-Si), polysilicon (p-Si), and/or crystalline silicon (c-Si).

In certain embodiments, when an upper portion of an amorphous silicon(a-Si) layer melted according to the melting annealing process ischanged to polysilicon (p-Si), the change in reflectivity may also berepresented by a graph.

For example, the data processing unit 44 of the control board 40according to the embodiment may predict the failure of the previousprocess or predict a material change before and after the meltingannealing process by predicting the type of the film coated on the waferW based on data about the reflectivity measured by the monitoring laserunit 20.

FIG. 11 is a graph illustrating another example of change inreflectivity measured by the monitoring device 2 according to theembodiment. FIG. 12 is a diagram for explaining that reflectivity mayvary according to the melting depth.

Referring to FIGS. 11 and 12, the melting depth of the upper portion ofthe wafer W may also be predicted by analyzing the period of change inreflectivity.

As apparent from FIG. 12, a deep melting depth may result in a longerperiod of change in reflectivity than a shallow melting depth. Forexample, different melting depth may result in different graphs.

For example, when the melting depth is a first depth which isshallowest, the change in reflectivity may be represented by a graph D1.When the melting depth is a third depth which is deepest, the change inreflectivity may be represented by a graph D3. When the melting depth isa second depth which is between the first depth and the third depth, thechange in reflectivity may be represented by a graph D2.

Accordingly, the data processing unit 44 of the control board 40according to the embodiment may predict/estimate the melting depth basedon data about the reflectivity measured by the monitoring laser unit 20.

FIG. 13 is a diagram for explaining the operation of measuring thetemperature of the surface of the wafer W using the monitoring device 2of FIG. 2.

Referring to FIG. 13, the thermal detecting unit 30 may include thethermal sensor 300, the lens 310, and the filter 311.

The thermal detecting unit 30 senses heat 32 emitted from the wafer Wwhile the processing laser unit 10 performs a melting annealing process.The heat 32 is emitted from the wafer W and passes through the lens 310and the filter 311 to reach the thermal sensor 300.

In an embodiment, the filter 311 may be a filter for passing awavelength of, e.g., 1550 nm of the heat 32 emitted from the wafer W.

For example, when the processing laser unit 10 performs a meltingannealing process on the wafer W on a die-by-die basis as described withrespect to FIG. 3, the thermal detecting unit 30 may detect the firsttemperature of the surface of the first die D1 while the processinglaser unit 10 performs the first melting annealing process on the firstdie D1 and then detect the second temperature of the surface of thesecond die D2 while the processing laser unit 10 performs the secondmelting annealing process on the second die D2.

The data processing unit 44 may then monitor the characteristics of thewafer W based on data about the first temperature and the secondtemperature measured by the thermal detecting unit 30.

FIG. 14 is a graph illustrating the relationship between the temperatureof the wafer surface and the melting depth.

Referring to FIG. 14, the temperature of the surface of the wafer Wmeasured by the thermal detecting unit 30 and the melting depth of theupper portion of the wafer W may have a substantially proportionalrelationship. Therefore, when the temperature TMP1 is relatively low asa result of analyzing the change in temperature, it may bepredicted/estimated that the melting depth DEP1 of the upper portion ofthe wafer W is relatively shallow. Conversely, when the temperature TMP2is relatively high, it may be predicted that the melting depth DEP2 ofthe upper portion of the wafer W is relatively deep.

Accordingly, the data processing unit 44 of the control board 40according to the embodiment may predict/estimate the melting depth basedon data about the temperature measured by the thermal detecting unit 30.

FIG. 15 is a graph illustrating the relationship between the temperatureof the wafer surface and the sheet resistance.

Referring to FIG. 15, the temperature of the surface of the wafer Wmeasured by the thermal detecting unit 30 and the sheet resistance ofthe wafer W may have a substantially inversely proportionalrelationship. Therefore, when the temperature TMP1 is relatively low asa result of analyzing the change in temperature, it may bepredicted/estimated that the sheet resistance Rs2 of the wafer W isrelatively high. Conversely, when the temperature TMP2 is relativelyhigh, it may be predicted that the sheet resistance Rs1 of the wafer Wis relatively low.

Accordingly, the data processing unit 44 of the control board 40according to the embodiment may predict the sheet resistance based ondata about the temperature measured by the thermal detecting unit 30.For example, with respect to an know material, e.g., amorphous silicon,polysilicon, crystalline silicon or another semiconductor material, themonitoring device 2 may be stored with data representing sheetresistances and corresponding surface temperature of the wafer W so thatthe data processing unit 44 may predict/determine the sheet resistancebased on the temperature data.

FIGS. 16 and 17 are diagrams for explaining a monitoring device 3according to an embodiment.

Referring to FIG. 16, the monitoring device 3 according to theembodiment is different from the monitoring device 2 of FIG. 2 in that amonitoring laser unit 20 further includes a beam split optics unit 240.

The beam split optics unit 240 splits a monitoring laser beam 22 c,which is to be incident on a die D formed on a wafer W, into a pluralityof beams. For example, the beam split optics unit 240 may split themonitoring laser beam 22 c (shown in FIG. 18) into a plurality of beamsso that the plurality of beams are incident on a die D of the wafer W.The beam split optics unit 240 may be a beam splitter.

Referring to FIG. 17, when the split monitoring laser beam 22 d isincident on the die D, a cross section of the incident light 22 e may berepresented by a plurality of points/areas B through B5 on the die D,unlike in FIG. 5.

The monitoring laser unit 20 then measures the reflectivity of each ofthe points/areas B1 through B5 on the die D.

It should be noted that the configuration of the monitoring device 3illustrated in FIG. 17 is merely an example embodiment, and the detailedconfiguration of a processing laser unit 10, the monitoring laser unit20 and a thermal detecting unit 30 may be modified variously accordingto the purpose of implementation.

FIGS. 18 and 19 are diagrams for explaining the operation of measuringthe reflectivity of a wafer W using the monitoring device 3 of FIG. 16.

Referring to FIG. 18, the monitoring laser unit 20 may include amonitoring laser emitter 200, a first light receiving unit 210, a secondlight receiving unit 212, lenses 220, 223 and 225, path changing optics221 and 227, filters 224 and 226, and the beam split optics unit 240.

The monitoring laser emitter 200 of the monitoring laser unit 20 emitsthe monitoring laser beam 22 c while the processing laser unit 10performs a melting annealing process using a processing laser beam 12.The monitoring laser beam 22 c passes through the lens 220 and isconverted into the split monitoring laser beam 22 d by the beam splitoptics unit 240. For example, the split monitoring laser beam 22 d maybe formed of a plurality of separated laser beams as shown in FIG. 17.For example, the cross-sectional area connecting the outer most parts ofthe laser beams of the plurality of laser beams of the split monitoringlaser beam 22 d may be greater than the cross-sectional area of themonitoring laser beam 22 c emitted from the monitoring laser emitter200. For example, the plurality of laser beams of the split monitoringlaser beam 22 d may travel parallel to one another. The split monitoringlaser beam 22 d changes its traveling direction to the wafer W accordingto the path changing optics 221. The split monitoring laser beam 22 dthat has changed its traveling direction travels to the first lightreceiving unit 210 and a path changing optics 111 according to the pathchanging optics 227. For example, the path changing optics 227 maycontrol the path of the split monitoring laser beam 22 d so that thesplit monitoring laser beam 22 d may transmit (e.g., by reflectionand/or refraction) to the first light receiving unit 210 in a firstperiod of time and to the path changing optics 111 and/or to the dies Din a second period of time. In certain embodiments, a part of the splitmonitoring laser beam 22 d is incident to the first light receiving unit210, and another part of the split monitoring laser beam 22 d isincident to the path changing optics 111 and/or to the dies D by thepath changing optics 227.

The first light receiving unit 210 receives reference light 22 ftraveling along a path branched by the path changing optics 227. Forexample, the reference light 22 f travelling along the path branchedfrom the split monitoring laser beam 22 d by the path changing optics227 passes through the lens 223 and the filter 224 and enters the firstlight receiving unit 210. In an embodiment, the filter 224 may be afilter for passing light having a wavelength of, e.g., 658 nm.

The split monitoring laser beam 22 d travelling to the path changingoptics 111 may pass through a lens 112 and enter the wafer W. Here,referring again to FIG. 17, when the split monitoring laser beam 22 d isincident on a die D, the cross section of the incident light 22 e may berepresented by the points/areas B1 through B5 as illustrated in FIG. 17.

Next, referring to FIG. 19, the second light receiving unit 212 receivessplit reflected light 23 a reflected from the wafer W. The splitreflected light 23 a passes through the lens 112 and the path changingoptics 111 and then changes its travelling direction to the second lightreceiving unit 212 according to the path changing optics 227. The splitreflected light 23 a that has changed its traveling direction passesthrough the lens 225 and the filter 226 and enters the second lightreceiving unit 212 as shown in FIG. 19. In an embodiment, the filter 226may be a filter for passing light having a wavelength of, e.g., 658 nm.

The monitoring laser unit 20 may measure reflectivity using the firstlight receiving unit 210 and the second light receiving unit 212. Forexample, the monitoring laser unit 20 may measure reflectivity bycomparing the intensity of the reference light 22 f received through thefirst light receiving unit 210 with the intensity of the split reflectedlight 23 a received through the second light receiving unit 212 for eachof the points/areas B1 through B5.

For example, when the processing laser unit 10 performs a meltingannealing process on the wafer W on a die-by-die basis as described withrespect to FIG. 3, the monitoring laser unit 20 may measure firstreflectivity of a first die D1 and second reflectivity of a second dieD2 by comparing the intensities of the split monitoring laser beam 22 dincident on the first die D1 and the second die D2 with the intensitiesof the split reflected light 23 a reflected from the first die D and thesecond die D2, respectively.

Here, the first light receiving unit 210 may receive the splitmonitoring laser beam 22 d incident on the first die D1 and the seconddie D2, the second light receiving unit 212 may receive the splitreflected light 23 a reflected from the first die D1 and the second dieD2, and the monitoring laser unit 20 may measure reflectivity by usingthe first light receiving unit 210 and the second light receiving unit212. For example, the first light receiving unit 210 may examine theintensity of the split monitoring laser beam 22 d by receiving the wholebeam or a partial beam of the split monitoring laser beam 22 d. In theembodiment that the first light receiving unit 210 receives a partialbeam of the split monitoring laser beam 22 d, the data processing unit44 may calculate the intensity of the split monitoring laser beam 22 dto be proportional to the intensity of the partial beam by using apredetermined parameter.

FIG. 20 is a diagram for explaining the operation of measuring thetemperature of the surface of the wafer W using the monitoring device 3of FIG. 16.

Referring to FIG. 20, the thermal detecting unit 30 may sense heat 32emitted from the wafer W as described with respect to FIG. 13, inconnection with the monitoring laser unit 20 of FIGS. 18 and 19 usingthe beam split optics unit 240.

FIG. 21 is a schematic diagram of a monitoring system 4 according to anembodiment.

Referring to FIG. 21, the monitoring system 4 according to theembodiment may include a processing laser unit 10, a monitoring laserunit 20, a thermal detecting unit 30 and a control board 40, and thecontrol board 40 may include a control unit 42, a data processing unit44 and a feedback unit 46.

The feedback unit 46 provides the control unit 42 with feedback data onthe characteristics of a wafer W monitored by the monitoring laser unit20 and the thermal detecting unit 30. The control unit 42 receiving thefeedback data may control the setting of at least one of the processinglaser unit 10, the monitoring laser unit 20, and the thermal detectingunit 30 based on the feedback data. For example, the control unit 42 mayperform control such as changing the wavelength of a processing laserbeam 12 emitted from the processing laser unit 10, adjusting the power,or adjusting the emission time. For another example, the control unit 42may perform control such as changing the wavelength of a monitoringlaser beam 22 emitted from the monitoring laser unit 20 or adjusting theemission time. The feedback unit 46 may be a feedback circuit, and maybe formed as an integrated circuit in a semiconductor chip and/or may beformed in a semiconductor device package.

Here, the feedback data refers to data for making an adjustment requestto the control unit 42 when a characteristic of the wafer W monitored ina previous operation needs to be adjusted. For example, when the meltingdepth is excessively deep, the feedback unit 46 may send to the controlunit 42 a request to lower the power of the processing laser beam 12 asthe feedback data. Conversely, when the melting depth is too shallow,the feedback unit 46 may send to the control unit 42 a request toincrease the power of the processing laser beam 12 as the feedback data.

FIG. 22 is a flowchart illustrating a monitoring method according to anembodiment.

Referring to FIG. 22, the monitoring method according to the embodimentincludes performing a melting annealing process on a wafer W by emittinga processing laser beam 12 to the wafer W (operation S2201).

The method also includes emitting a monitoring laser beam 22 to thewafer W (operation S2203) while the melting annealing process is beingperformed and measuring the reflectivity of the wafer W by comparing theintensity of the monitoring laser beam 22 with the intensity ofreflected light 23 (operation S2205). For example the intensity of themonitoring laser beam 22 may be an intensity of light of the monitoringlaser beam 22, and the intensity of reflected light 23 may be anintensity of light that the monitoring laser beam 22 is reflected from asurface of the wafer W.

The method also includes measuring the temperature of the surface of thewafer W (S2207) while the melting annealing process is performed.

The method also includes analyzing the characteristics of the wafer Wbased on data about the measured reflectivity and/or temperature(operation S2209).

FIG. 23 is a flowchart illustrating a monitoring method according to anembodiment.

Referring to FIG. 23, the monitoring method according to the embodimentincludes heating and monitoring a first wafer (operation S2301) andanalyzing first characteristics of the first wafer (operation S2303).

The method also includes heating and monitoring a second wafer(operation S2305) and analyzing second characteristics of the secondwafer (operation S2307).

The method also includes comparing the first characteristics of thefirst wafer with the second characteristics of the second wafer(operation S2309).

According to the present method, the uniformity of melting depth betweenwafers may be compared and in-situ monitoring may be performed so as tocompare changes in grain size between wafers.

FIG. 24 is a flowchart illustrating a monitoring method according to anembodiment.

Referring to FIG. 24, the monitoring method according to the embodimentincludes performing a melting annealing process on a wafer W by emittinga processing laser beam 12 to the wafer W (operation S2401).

The method also includes emitting a monitoring laser beam 22 to thewafer W (operation S2403) while the melting annealing process isperformed and measuring the reflectivity of the wafer W by comparing theintensity of the monitoring laser beam 22 with the intensity ofreflected light 23 (operation S2405).

The method also includes measuring the temperature of the surface of thewafer W (operation S2407) while the melting annealing process isperformed.

The method also includes adjusting the power of the processing laserbeam 12 based on data about the measured reflectivity and/or temperature(operation S2409).

According to the monitoring devices and the monitoring methods of thevarious embodiments described so far, even if a melting process isperformed for a very short time of several nanoseconds to several tensof nanoseconds, in-situ monitoring of the melting process may beaccurately performed during that time, and in-situ identification of thecharacteristics of a wafer may be performed while the melting annealingprocess is performed.

For example, while the melting annealing process is performed, amonitoring laser is emitted to the wafer, and reflected light isreceived. Then, a change in the reflectivity of the wafer is defined asa kind of reference pattern, and a change in reflectivity in asubsequent process is compared with the reference pattern. In this way,in-situ monitoring may be performed, and the characteristics of thewafer may be predicted. While the melting annealing process isperformed, in-situ monitoring may be also performed and thecharacteristics of the wafer may be predicted by sensing heat emittedfrom the wafer.

Furthermore, the power of a processing laser may be controlled by usingthe result of analyzing the wafer characteristics or the processdispersion may be controlled through comparison between wafers.

A method of manufacturing a semiconductor device according to anembodiment of the present disclosure will be described below.

According to the method of manufacturing a semiconductor device, asubstrate may be provided. The substrate may be a semiconductorsubstrate, for example, a silicon substrate, a germanium substrate or asilicon-germanium substrate. Various semiconductor patterns and variousconductor patterns may be formed on the substrate to form circuitsincluding transistors, capacitors and/or switches via a plurality ofmanufacturing processes including multiple steps of photolithographyprocesses. One or more melting annealing processes may be appliedbefore, between and/or after performing the plurality of manufacturingprocesses. During the melting annealing processes, a monitoring methoddescribed in various embodiments of the present disclosure may beapplied to the substrate. In certain embodiments, the melting annealingprocesses may adjust the process conditions using a result of themonitoring obtained by a monitoring method described in the presentdisclosure. After forming various circuits on the substrate, thesubstrate may be diced and packaged.

In concluding the detailed description, those skilled in the art willappreciate that many variations and modifications may be made to thepreferred embodiments described above without substantially departingfrom the principles of the present disclosure. Therefore, the disclosedpreferred embodiments of the disclosure are used in a generic anddescriptive sense only and not for purposes of limitation.

What is claimed is:
 1. A monitoring device comprising: a laser processorconfigured to emit a processing laser beam to perform a meltingannealing process on a wafer; a laser monitor configured to emit amonitoring laser beam onto the wafer while the laser processor performsthe melting annealing process, the laser monitor configured to measurereflectivity of the wafer; and a data processor configured to processdata on the reflectivity measured by the laser monitor, and monitor oneor more characteristics of the wafer based on the data on thereflectivity.
 2. The monitoring device of claim 1, wherein the lasermonitor is configured to measure the reflectivity by comparing intensityof the monitoring laser beam incident on the wafer with intensity of areflection of the monitoring laser beam from the wafer.
 3. Themonitoring device of claim 2, wherein the laser monitor comprises afirst light sensor configured to receive the monitoring laser beamincident on the wafer and a second light sensor configured to receivethe reflection of the monitoring laser beam coming from the wafer, andwherein the laser monitor is configured to measure the reflectivity byusing the first light sensor and the second light sensor.
 4. Themonitoring device of claim 1, wherein the laser monitor is configured tomeasure the reflectivity of the wafer for each die formed on the wafer.5. The monitoring device of claim 1, wherein the laser monitor furthercomprises a beam splitter configured to split the monitoring laser beaminto a plurality of beams, and wherein the laser monitor is configuredto measure the reflectivity at a plurality of points in a die on whichthe plurality of beams is incident.
 6. The monitoring device of claim 1,further comprising a thermal detector configured to detect a temperatureof a surface of the wafer while the laser processor performs the meltingannealing process, wherein the data processor is configured to processdata on the temperature measured by the thermal detector, and monitorthe characteristics of the wafer based on the data on the temperature.7. The monitoring device of claim 6, wherein the thermal detector isconfigured to detect the temperature of the surface of the wafer foreach die formed on the wafer.
 8. The monitoring device of claim 1,further comprising: a controller configured to control the laserprocessor; and a feedback circuit configured to provide the controllerwith feedback data on the monitored characteristics of the wafer,wherein the controller is configured to adjust power of the processinglaser beam according to the feedback data.
 9. The monitoring device ofclaim 1, wherein the wafer is a first wafer and the data processor isconfigured to monitor first characteristics of the first wafer andsecond characteristics of a second wafer and to compare the firstcharacteristics and the second characteristics.
 10. A monitoring devicecomprising: a support configured to receive a wafer comprising a firstdie and a second die; a laser processor configured to perform a firstmelting annealing process by emitting a processing laser beam to thefirst die and a second melting annealing process by emitting theprocessing laser beam to the second die; first and second light sensors;a laser monitor configured to measure first reflectivity of the firstdie in combination with the first and second light sensors by emitting amonitoring laser beam to the first die while the laser processorperforms the first melting annealing process, the laser monitorconfigured to measure second reflectivity of the second die incombination with the first and second light sensors by emitting themonitoring laser beam to the second die while the laser processorperforms the second melting annealing process; and a data processorconfigured to monitor characteristics of the wafer based on the firstreflectivity and the second reflectivity measured by the laser monitor.11. The monitoring device of claim 10, wherein the laser monitor isconfigured to measure the first reflectivity and the second reflectivityby comparing intensities of the monitoring laser beam incident on thefirst die and the second die with intensities of light reflected fromthe first die and the second die respectively.
 12. The monitoring deviceof claim 11, wherein the laser monitor comprises: the first light sensorconfigured to receive the monitoring laser beam incident on the firstdie and the second die; and the second light sensor configured toreceive the light reflected from the first die and the second die, andwherein the laser monitor is configured to measure the firstreflectivity and the second reflectivity by using the first light sensorand the second light sensor.
 13. The monitoring device of claim 10,wherein the laser monitor further comprises a beam splitter configuredto split the monitoring laser beam, which is to be incident on the firstdie, into a plurality of beams and to split the monitoring laser beam,which is to be incident on the second die, into a plurality of beams,and wherein the laser monitor is configured to measure the firstreflectivity at a plurality of points in the first die on which theplurality of split monitoring laser beams is incident and to measure thesecond reflectivity at a plurality of points in the second die on whichthe plurality of split monitoring laser beams is incident.
 14. Themonitoring device of claim 10, further comprising a thermal detectorconfigured to detect a first temperature of a surface of the first diewhile the laser processor performs the first melting annealing processand to detect a second temperature of a surface of the second die whilethe laser processor performs the second melting annealing process,wherein the data processor is configured to monitor the characteristicsof the wafer based on the first temperature and the second temperaturemeasured by the thermal detector.
 15. The monitoring device of claim 10,wherein the wafer is a first wafer, wherein the data processor isconfigured to monitor first characteristics of the first wafer andsecond characteristics of a second wafer, and wherein the data processoris configured to compare the first characteristics and the secondcharacteristics.
 16. A monitoring device comprising: a laser processorconfigured to perform a melting annealing process on a wafer by emittinga processing laser beam to the wafer; first and second light sensorsconfigured to receive light signal; a laser monitor configured tomeasure reflectivity of the wafer in combination with the first andsecond light sensors by emitting a monitoring laser beam to the waferwhile the laser processor performs the melting annealing process; athermal detector configured to detect temperature of a surface of thewafer while the laser processor performs the melting annealing process;a controller configured to control at least one of the laser processor,the laser monitor and the thermal detector; and a feedback circuitconfigured to provide the controller with feedback data according to avalue of at least one of the measured reflectivity and temperature,wherein the controller is configured to adjust a setting of at least oneof the laser processor, the laser monitor and the thermal detectoraccording to the feedback data.
 17. The monitoring device of claim 16,wherein the laser monitor is configured to measure the reflectivity bycomparing intensity of the monitoring laser beam incident on the waferwith intensity of light reflected from the wafer.
 18. The monitoringdevice of claim 17, wherein the first light sensor is configured toreceive the monitoring laser beam incident on the wafer and the secondlight sensor is configured to receive the light reflected from thewafer, and wherein the laser monitor is configured to measure thereflectivity by using the first light sensor and the second lightsensor.
 19. The monitoring device of claim 16, wherein the laser monitorand the thermal detector are respectively configured to measure thereflectivity and temperature of the water for each die formed on thewafer.
 20. The monitoring device of claim 16, wherein the laser monitorfurther comprises a beam splitter configured to split the monitoringlaser beam, which is to be incident on a die formed on the wafer, into aplurality of beams, and wherein the laser monitor is configured tomeasure the reflectivity at a plurality of points in the die on whichthe plurality of beams is incident.